Shoulder pain is a common complication following stroke, affecting almost one third of stroke survivors. Of the multitude of treatment options, only surface electrical stimulation has evidence of efficacy from multiple randomized controlled trials. However, clinical and technical difficulties associated with surface stimulation, such as discomfort caused by stimulation of cutaneous pain receptors and the need for skilled personnel to place the surface electrodes on a daily basis, have prevented it from becoming the standard of care. Percutaneous electrical stimulation is a promising treatment option, as demonstrated by clinical studies, but there are no commercially available systems. During the Phase I project period, the design concept for a novel percutaneous electrical stimulation system was completed and its technical feasibility was demonstrated. The objective of this Phase II project is to complete the design and development of the electrical stimulator and assess its usability, safety, and efficacy in a technical and clinical validation study. The specific aims of this project are to 1) complete the development of the stimulator housing and construction, 2) complete the development and testing of the stimulator's miniaturized circuit board and associated embedded software, and 3) conduct a clinical study to validate the usability, safety, and efficacy of the Neuropill System in eleven subjects with post-stroke shoulder pain. Our long term goal is to commercialize a safe and effective therapy for post-stroke shoulder pain. At the conclusion of this Phase II project, we will have completed the development of an innovative technology and evaluated its usability, safety, and efficacy for the treatment of post-stroke shoulder pain. Ultimately, the findings from this development effort and clinical validation study will enable us to design and initiate the larger clinical studies necessary for commercialization. PUBLIC HEALTH RELEVANCE: Present treatment options for post-stroke shoulder pain, affecting almost one third of stroke survivors, are either ineffective or have technical barriers preventing their widespread use. Percutaneous electrical stimulation is a promising treatment option, as demonstrated by clinical studies, but there are no commercially available systems. The Neuropill System is intended to provide electrical stimulation therapy to significantly reduce post-stroke shoulder pain, while offering significant advantages in comfort, patient compliance, and ease of use.